Propensity score matched comparison of docetaxel and androgen receptor axis-targeted (ARAT) agents in castration-resistant prostate cancer patients with intraductal carcinoma of the prostate (IDC-P).

Abstract

80 Background: Several studies have reported that intraductal carcinoma of the prostate (IDC-P) is a pathological adverse prognostic factor in patients with prostate cancer. However, the optimal treatment has not been established. The present study aimed to evaluate the efficacy of docetaxel and androgen receptor axis-targeted (ARAT) agents in patients with castration-resistant prostate cancer (CRPC) with IDC-P using a propensity score-matched analysis. Methods: We retrospectively identified 309 patients with CRPC from February 2007 to February 2016. They received initial androgen deprivation therapy (ADT) and after progression to CRPC, they received docetaxel or ARAT (abiraterone or enzalutamide) as the first-line life-prolonging therapy. The primary outcome of interest was OS from the time of CRPC diagnosis. We also investigated PFS from the time of docetaxel or ARAT initiation. Results: Propensity score-matching identified 85 patients in each group. There were no significant differences in patient characteristics between the groups. The median OS in the docetaxel group was 38.2 months versus 58.3 months in the ARAT group (HR 0.57; 95% CI 0.37–0.89; P =.01). Regarding patients with IDC-P, OS was significantly longer in the ARAT group than the docetaxel group (HR 0.48; 95% CI 0.26–0.86; P =.01), and there was no significant difference in each group, as in patients without IDC-P (HR 0.75; 95% CI 0.37–1.52; P =.43). The median PFS in the docetaxel group was 6.7 versus 7.8 months in the ARAT group (HR 0.65; 95% CI 0.45–0.94; P =.02). A multivariate analysis demonstrated that the presence of IDC-P, duration of primary ADT, visceral metastasis, and administration of ARAT as the first treatment for CRPC were independent prognostic factors for OS. Conclusions: Administration of ARAT as the first treatment for CRPC may prolong OS more than that of docetaxel, especially in patients with IDC-P.